The fantastic Toy Soldiers is now, after calling XBLA home for over two years, available on PC for all you unlucky people who don't own an Xbox 360. It's a bit sad to see only the original and not the sequel—Toy Soldiers: Cold War improves upon the original in practically every way—but something is better than nothing and right now you can grab the game for 25% off on Steam. (The game is worth the price whether on sale or not; hell, it used to be $15 on XBLA.)
If you don't know anything about Toy Soldiers, it's basically a tower defense game where you can control individual towers—which you'll want to do because you'll always be more productive—level-specific vehicles like tanks and biplanes, or just sit back and watch as your army is decimated. The old school, toy soldier theme is charming and well-utilized and brought back memories of the days when I was a wee little boy playing with actual toy soldiers.
There's plenty of content and a good amount of adjustable challenge in the single-player, but I haven't played the PC port and it appears to be stripped of all forms of multiplayer—which is very disappointing if true. That said, the game is still a lot of fun sans all multiplayer components and I'd recommend it to any fan of tower defense games. I really wish there was a demo because nothing could sell the game better than the game itself.
Toy Soldiers (Steam)